A Thin film transistor Liquid Crystal Display (TFT-LCD), as a flat-panel display device, is more and more frequently applied to a high-performance display field, due to characteristics such as small size, low power consumption, no radiation and relatively low fabrication cost.
The TFT-LCD is mainly comprised of an array substrate and a color filter substrate. Liquid crystals are filled between the array substrate and the color filter substrate; by controlling deflection of the liquid crystal, control of light intensity can be implemented; and by a filtering function of the color filter substrate, color image display is implemented.
An existing TFT-LCD fabrication process mainly includes four stages, which are color filter substrate fabrication process, Array (array substrate fabrication) process, Cell (liquid crystal cell fabrication) process, and Module (module assembly) process respectively. As an important process in TFT-LCD production, the Array process is usually forming a separate thin film transistor (TFT) array circuit on a glass substrate, and quality of the array circuit will directly affect display quality of a product. However, in an actual production process, undesirable phenomena such as Mura, dark spot and chromatic aberration will occur to the array substrate, due to influence of its production environment, a technological level, or other factors, thus seriously affecting display effect of a display device.
Therefore, in order to avoid the above-described undesirable phenomena, characteristics of the TFT can be tested by a test apparatus. For example, an on-current Ion and an off-current Ioff of the TFT, temperature sensitivity or light sensitivity of the TFT, and other performance parameters are tested. In a related art, a test element located on a peripheral region of a display panel may be tested. However, data obtained from the tested element cannot directly and truly reflect the actual characteristics of the TFT within respective pixel units on the array substrate, thus reducing accuracy of a test result.